Multiple function safe and arm mechanism

ABSTRACT

A safe and arm mechanism for use with a proximity fuze which uses an active battery and which is armed by spin. The mechanism includes an electric detonator which is short-circuited and misaligned with respect to a lead when the mechanism is in an unarmed position, and a battery switch which is off when the mechanism is in an unarmed position. Spinning causes the arming weights in the mechanism to rotate and to release a slider which removes the short-circuit, brings the lead into alignment with the electric detonator, and causes the battery switch to turn on the battery to fully arm the fuze.

Webb et a1.

[ 1 MULTIPLE FUNCTION SAFE AND ARM MECHANISM [75] Inventors: George Webb; Bernard L. Malott,

both of Richmond, Ind.

22 Filed: Feb. 23, 1971 21 Appl. No.: 118,012

[52] US. Cl... l02/70.2 R, 102/79, 102/702 P [51] Int. CL... F42c 13/00, F420 11/00, F42c 15/22 [58] Field of Search 102/702, 79

[56] References Cited UNITED STATES PATENTS 3,381,613 5/1968 Webb 102/70.2 2,925,777 2/1960 Crozier... 2,801,589 8/1057 Meek et al 102/78 3,587,469 6/1971 Gratton et a1. 102/79 Primary Examiner-Benjamin A. Borchelt Assistant ExaminerThomas H. Webb Attorney-Harry A. Herbert, Jr. and Arsen Tashjian [5 7] ABSTRACT A safe and arm mechanism for use with a proximity fuze which uses an active battery and which is armed by spin. The mechanism includes an electric detonator which is short-circuited and misaligned with respect to a lead when the mechanism is in an unarmed position, and a battery switch which is off when the mechanism is in an unarmed position. Spinning causes the arming weights in the mechanism to rotate and to release a slider which removes the short-circuit, brings the lead into alignment with the electric detonator, and causes the battery switch to turn on the battery to fully arm the fuze.

5 Claims, 2 Drawing Figures PATENIEUIIEEZSIUTS MULTIPLE FUNCTION SAFE AND ARM MECHANISM BACKGROUND OF THE INVENTION This invention relates to a safe and arm mechanism which uses an active battery and which is armed by spin for use with a proximity fuze.

In the prior art; slider type safe and arm mechanism, such as this invention, used arming weights which moved in a groove that was part of the housing. Such a safe and arm mechanism was very rugged and gave good results when the slider was of lightweight material, such as nylon, and when the arming weights could be made relatively long and of material of high density, such as brass. As the fuze became smaller, and as the number of functions to be performed by the slider became greater, the mass and the displacement of the arming weights became critical factors. The slider was then changed from a lightweight material to brass to give the required inertial force to operate the shortcircuit switch and the battery switch. This change of the slider caused frictional forces on the arming weights; these frictional forces were overcome by changing the material, of which the arming weights were made, from brass to tungsten. However, tungsten is expensive and is difficult to machine.

A prior art mechanism, such as described above, is disclosed and claimed in U. S. Pat. No. 3,381,613, which was issued on May 7, 1968, to George Webb, an inventor of the invention herein.

All factors considered, it would appear that a nearly ideal safe and arm mechanism of the slider type would not need the guidance type of support which a conventional sliding arming weight needs, would minimize the frictional forces or frictional points, and would allow the use of larger arming weights.

We have invented such a safe and arm mechanism and have thereby significantly advanced the state-ofthe-art.

SUMMARY OF THE INVENTION This invention relates to a safe and arm mechanism of the slider type.

The principal object of this invention is to provide a slider type safe and arm mechanism for spin armed fuzes of the proximity type.

Another object of this invention is to provide a safe and arm mechanism which will perform all arming functions using centrifugal force only.

Still another object of this invention is to provide a slider type safe and arm mechanism which uses rotating, rather than sliding, arming weights to minimize the frictional forces present at the time of arming, with the rotating arming weights being larger than the conventional sliding arming weights.

A further object of this invention is to provide a slider type safe and arm mechanism which utilizes the motion of the slider to turn an active battery on, to remove a short-circuit from the electric detonator, and to align a lead to the detonator of the explosive train.

These and other related objects of this invention will become readily apparent from a consideration of the description of the invention and reference to the drawmgs.

DESCRIPTION OF THE DRAWINGS FIG. I is a top view, partially in cross-section and partially in schematic form, of a preferred embodiment of the invention; and

FIG. 2 is a side view of the preferred embodiment shown in FIG. ll, partially in cross-section and partially in diagrammatic form, taken along line Illl of FIG. 1, looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 1 and 2, wherein the same component is denoted by the same reference numeral, therein is shown a preferred embodiment III of our invention. Also shown is spin axis A-B, FIG. 2, of preferred embodiment 110, which is also the longitudinal axis of embodiment 1t).

Embodiment Ml includes a housing which in turn includes cylindrical cover 211 and end plug 22 which, when fitted together, from the housing or enclosure within which the other components of embodiment 10 are disposed.

The other components of embodiment 10 include a frame 30 which is attached to housing cover 21; an active battery 40 attached to housing plug 22; a battery switch 41 attached to frame 30 and connected to active battery 40; an electric detonator attached to frame 30; an electric short-circuit switch 60 attached to frame 30 and imposing a short-circuit on the electric detona- I tor 50; two arming weights 71 and 72 pivotally connected to frame 30 by pivots 73 and 74; a slider 80 interposed between and mechanically engaged with arming weights 711 and 72; two arming springs 75 and 76, one on the side of arming weight 71 and the other on the side of arming weight 72, with springs 75 and 76 holding arming weights 711 and 72 in engagement with slider 30; and two abutments 91 and 92 on frame 30, with an abutment on each side of slider 80, and with abutments 911 and 92 so positioned that the distance between abutments 911 and 92 at the outer edge, said distance designated C, is more than the width designated D of slider 80.

Also shown are misaligned detonator explosive train lead 100; ends 81 and 82 of slider 80; fastener 61 of electric short-circuit switch 60; lead 42 which connects active battery 40 to battery switch 411; and aperture 23 in housing cover 21.

Not shown, because it is not part of the invention, is the electric circuitry which is energized by active battery 40 to tire detonator 50. That circuitry is part of the fuze (not shown) of which this invention, the safe and arm mechanism, is also a part.

Referring again to the drawings, it is to be noted that battery switch 4ll, as shown in FIG. 2, is in the off position; that slider has two ends, 811 and 82, with end 81 interposed between electric short-circuit switch 60 and battery switch it, and with other end 82 positioned between abutments 911 and 92, FIG. I; that the distance C between abutments 91 and 92 at the outer edge is more than the width D of end 82 of slider Ml; this misaligned lead lltltl of electric detonator 50 is within slider 80; that slider 80 is positioned for movement perpendicular to the spin axis A-B of embodiment I0; and that the central axis, i.e., spin axis, of the fuze of which embodiment I0 is a part, is coincident with spin axis A-lB of embodiment It).

aluminum and that slider 80 is preferably of brass.

MODE OF OPERATION OF THE PREFERRED EMBODIMENT As has been previously stated, the invention is adapted for use with a spin armed fuze of the proximity t e.

\iVhen such a fuze and this invention are installed in a bomb and the bomb is air-dropped and reaches the required, i.e., predetermined rate of spin; centrifugal force acts on arming weights 71 and 72 and overcomes the force of arming springs 75 and 76. As a result, arming weights 7!. and 72 move outwardly, compressing arming springs 75 and 76, and disengaging arming weights 71 and 72 from slider 80. Simultaneously, slider 80 is freed by and from arming weights 71 and 72 and moves radially in a direction perpendicular to spin axis and central axis A-B. Thereby, short-circuit switch 60 and battery switch 41 come into and remain in contact, removing, i.e. eliminating, the short-circuit; misaligned lead 100 of electric detonator 50 comes into alignment with detonator 50 and aperture 23, permitting the explosing of the detonator explosive train (not shown) when the fuze (not shown) is in the vicinity of the target; and battery switch 41 moves forward and into the on position, allowing active battery 40 to be turned on and, thus, fully arming the fuze.

While there have been shown and described the fundamental features of the invention, as applied to a preferred embodiment, it is to be understood that various substitutions and omissions may be made by those of ordinary skill in the art without departing from the spirit of the invention.

As a related matter, it is to be remembered that a prior art device is disclosed and claimed in U. S. Pat. No, 3,381,613 which was issued on May 7, 1968, to George Webb, an inventor of the present invention. Some of the significant differences between that prior art device and the present invention are: (a) the present invention uses arming weights which rotate about pivots or pins, such as 73 and 74, FIG. 1, in the frame, such as 30, FIGS. 1 and 2, and this feature greatly reduces the frictional loads during the arming cycle, since the only significant rubbing action is between the arming weights, such as 71 and 72, FIG. 1, and the slider, such as 80, FIGS. 1 and 2; (b) it is possible to use relatively larger arming weights in the present invention, because the pivot type of arming weight, such as 71 and 72, FIG. 1, does not need the guidance type of support that a sliding type arming weight, such as 22 and 23, FIG. I, U. S. Pat. No. 3,381,613, needs; (c) the pivot type of arming weight, such as used in the present invention, allows the use of steel arming weights, rather than tungsten ones, with higher reliability; (d) a simple, off-the-shelf, commercially available battery switch may be used in the present invention replacing the special design shown as 41, FIG. 2; and (e) the loads to or on the battery switch, such as 41, FIG. 2, and shortcircuit switch, such as 60, FIGS. 1 and 2, act normal to the axis of the slider, such as 80, FIGS. 1 and 2, and thereby prevent the slider from creeping under vibration, jolting or jumbling.

What is claimed is:

l. A safe and arm mechanism of the slider type, having a spin axis, and for use with a proximity fuze which uses an active battery, comprising:

a. a housing;

b. a frame attached to said housing;

c. an active battery attached to said housing;

d. a battery switch, in the off position, attached to said frame and connected to said active battery;

e. an electric detonator, having a misaligned lead,

with said detonator attached to said frame;

f. an electric short-circuit switch attached to said frame and imposing a short-circuit on said electric detonator;

g. two arming weights pivotally connected to said frame;

h. a slider, having two ends, interposed between, and mechanically engaged with, said arming weights, with one end of said slider interposed between said electric short-circuit switch and said battery switch, and with said slider having therein said misaligned lead of said electric detonator, and with said slider positioned for movement perpendicular to the spin axis of the safe and arm mechanism;

. two springs, one on the side of each of said two arming weights, holding said arming weights in engagement with said slider;

j. and, two abutments on said frame, an abutment on each side of said slider, positioned so that the distance between the abutments at the outer edge is more than the width of said other end of said slider;

whereby when the safe and arm mechanism reaches the required threshold of spin, centrifugal force rotates said arming weights, releasing said slider which, thereby, removes the short-circuit, brings the misaligned lead in alignment with said electric detonator, and allows the battery switch to turn on the battery and, thereby, fully arms the fuze.

2. A safe and arm mechanism, as set forth in claim 1,

wherein said frame is of metal.

3. A safe and arm mechanism, as set forth in claim 2, wherein said frame is of aluminum.

4. A safe and arm mechanism, as set forth in claim 1, wherein said slider is of metal.

5. A safe and arm mechanism, as set forth in claim 4,

wherein said slider is of brass. 

1. A safe and arm mechanism of the slider type, having a spin axis, and for use with a proximity fuze which uses an active battery, comprising: a. a housing; b. a frame attached to said housing; c. an active battery attached to said housing; d. a battery switch, in the off position, attached to said frame and connected to said active battery; e. an electric detonator, having a misaligned lead, with said detonator attached to said frame; f. an electric short-circuit switch attached to said frame and imposing a short-circuit on said electric detonator; g. two arming weights pivotally connected to said frame; h. a slider, having two ends, interposed between, and mechanically engaged with, said arming weights, with one end of said slider interposed between said electric short-circuit switch and said battery switch, and with said slider having therein said misaligned lead of said electric detonator, and with said slider positioned for movement perpendicular to the spin axis of the safe and arm mechanism; i. two springs, one on the side of each of said two arming weights, holding said arming weights in engagement with said slider; j. and, two abutments on said frame, an abutment on each side of said slider, positioned so that the distance between The abutments at the outer edge is more than the width of said other end of said slider; whereby when the safe and arm mechanism reaches the required threshold of spin, centrifugal force rotates said arming weights, releasing said slider which, thereby, removes the short-circuit, brings the misaligned lead in alignment with said electric detonator, and allows the battery switch to turn on the battery and, thereby, fully arms the fuze.
 2. A safe and arm mechanism, as set forth in claim 1, wherein said frame is of metal.
 3. A safe and arm mechanism, as set forth in claim 2, wherein said frame is of aluminum.
 4. A safe and arm mechanism, as set forth in claim 1, wherein said slider is of metal.
 5. A safe and arm mechanism, as set forth in claim 4, wherein said slider is of brass. 